# pike.git/lib/modules/Calendar.pmod/Event.pmod

Branch: Tag:

## 2012-09-22

#### 2012-09-22 15:13:24 by Henrik GrubbstrĂ¶m (Grubba) <grubba@grubba.org>

• 4b1e0389e484cc4b6138280d5f5bd7818df3a15d (85 lines) (+2/-83) [ Show | Annotate ]
Branch: 7.9
Calendar: Moved deltat() to a more easily accessible place.

913:    ({ 0.00008, 0.2697, 294.24635, }),    });    -  //! Polynomial terms for calculating the difference between TDT and UTC. -  //! -  //! The polynomials have been taken from NASA: -  //! @url{http://eclipse.gsfc.nasa.gov/SEhelp/deltatpoly2004.html@} -  //! -  //! Each entry is an @expr{array(float)@}: -  //! @array -  //! @elem float 0 -  //! End year for the range. -  //! @elem float 1 -  //! Year offset. -  //! @elem float 2 -  //! Year divisor. -  //! @elem float 3.. -  //! Polynomial factors with the highest exponent first. -  //! @endarray -  protected constant deltat_polynomials = ({ -  ({ -500.0, -1820.0, 100.0, -  -20.0, 0.0, 32.0, }), -  ({ 500.0, 0.0, 100.0, -  0.0090316521, 0.022174192, -0.1798452, -  -5.952053, 33.78311, -1014.41, 10583.6, }), -  ({ 1600.0, -1000.0, 100.0, -  0.0083572073, -0.005050998, -0.8503463, -  0.319781, 71.23472, -556.01, 1574.2, }), -  ({ 1700.0, -1600.0, 1.0, -  0.000140272128, -0.01532, -0.9808, 120.0, }), -  ({ 1800.0, -1700.0, 1.0, -  0.000000851788756, 0.00013336, -0.0059285, 0.1603, 8.83, }), -  ({ 1860.0, -1800.0, 1.0, -  0.000000000875, -0.0000001699, 0.0000121272, -0.00037436, -  0.0041116, 0.0068612, -0.332447, 13.72, }), -  ({ 1900.0, -1860.0, 1.0, -  0.000004288643, -0.0004473624, 0.01680668, -0.251754, 0.5737, 7.62, }), -  ({ 1920.0, -1900.0, 1.0, -  -0.000197, 0.0061966, -0.0598939, 1.494119, -2.79, }), -  ({ 1941.0, -1920.0, 1.0, -  0.0020936, -0.076100, 0.84493, 21.20, }), -  ({ 1961.0, -1950.0, 1.0, -  0.0003926188, 0.0042918455, 0.407, 29.07, }), -  ({ 1986.0, -1975.0, 1.0, -  0.001392758, 0.0038461538, 1.067, 45.45, }), -  ({ 2005.0, -2000.0, 1.0, -  0.00002373599, 0.000651814, 0.0017275, -0.060374, 0.3345, 63.86, }), -  ({ 2050.0, -2000.0, 1.0, -  0.005589, 0.32217, 62.92 }), -  ({ 2150.0, -1820.0, 100.0, -  32.0-185.724, 56.28, -20.0, }), -  ({ Math.inf, -1820.0, 100.0, -  32.0, 0.0, -20.0, }), -  }); -  -  //! Terrestrial Dynamical Time difference from standard time. -  //! -  //! @returns -  //! Difference between TDT and UTC in seconds at the -  //! specified time. -  int deltat(int unadjusted_utc) -  { -  // Approximation of the year. This ought to be good enough for -  // most purposes given the uncertainty in the table values. -  // 31556952 == 365.2425 * 24 * 60 * 60. -  float y = 1970.0 + unadjusted_utc/31556952.0; -  -  array(float) polynomial; -  int l, c, h = sizeof(deltat_polynomials); -  do { -  c = (l + h)/2; -  polynomial = deltat_polynomials[c]; -  if (y < polynomial[0]) h = c; -  else l = c + 1; -  } while (l < h); -  float u = (y + polynomial[1])/polynomial[2]; -  -  float deltat = 0.0; -  foreach(polynomial; int i; float factor) { -  if (i < 3) continue; -  deltat = deltat * u + factor; -  } -  return (int)round(deltat); -  } -  +     //! Calculate the next event.    //!    //! Based on Meeus Astronomical Algorithms Chapter 27.
1118:       // Convert into an UTC timestamp.    int utc = (new_jd - 2440588)*86400 + (int)(offset * 86400.0); -  return utc - deltat(utc); +  return utc - (int)round(Calendar.ISO.deltat(utc));    }       Calendar.TimeRanges.TimeRange next(void|Calendar.TimeRanges.TimeRange from,